package main

import "fmt"

/*
Tic-tac-toe is played by two players A and B on a 3 x 3 grid.
Here are the rules of Tic-Tac-Toe:
Players take turns placing characters into empty squares (" ").
The first player A always places "X" characters, while the second player B always places "O" characters.
"X" and "O" characters are always placed into empty squares, never on filled ones.
The game ends when there are 3 of the same (non-empty) character filling any row, column, or diagonal.
The game also ends if all squares are non-empty.
No more moves can be played if the game is over.
Given an array moves where each element is another array of size 2 corresponding to the row and column of the grid where they mark their respective character in the order in which A and B play.
Return the winner of the game if it exists (A or B), in case the game ends in a draw return "Draw", if there are still movements to play return "Pending".
You can assume that moves is valid (It follows the rules of Tic-Tac-Toe), the grid is initially empty and A will play first.

Example 1:
Input: moves = [[0,0],[2,0],[1,1],[2,1],[2,2]]
Output: "A"
Explanation: "A" wins, he always plays first.
"X  "    "X  "    "X  "    "X  "    "X  "
"   " -> "   " -> " X " -> " X " -> " X "
"   "    "O  "    "O  "    "OO "    "OOX"

Example 2:
Input: moves = [[0,0],[1,1],[0,1],[0,2],[1,0],[2,0]]
Output: "B"
Explanation: "B" wins.
"X  "    "X  "    "XX "    "XXO"    "XXO"    "XXO"
"   " -> " O " -> " O " -> " O " -> "XO " -> "XO "
"   "    "   "    "   "    "   "    "   "    "O  "

Example 3:
Input: moves = [[0,0],[1,1],[2,0],[1,0],[1,2],[2,1],[0,1],[0,2],[2,2]]
Output: "Draw"
Explanation: The game ends in a draw since there are no moves to make.
"XXO"
"OOX"
"XOX"

Example 4:
Input: moves = [[0,0],[1,1]]
Output: "Pending"
Explanation: The game has not finished yet.
"X  "
" O "
"   "

Constraints:
1 <= moves.length <= 9
moves[i].length == 2
0 <= moves[i][j] <= 2
There are no repeated elements on moves.
moves follow the rules of tic tac toe.
*/

func main() {
	fmt.Println(tictactoe([][]int{{0, 0}, {2, 0}, {1, 1}, {2, 1}, {2, 2}}))
	fmt.Println(tictactoe([][]int{{0, 0}, {1, 1}, {0, 1}, {0, 2}, {1, 0}, {2, 0}}))
	fmt.Println(tictactoe([][]int{{0, 0}, {1, 1}, {2, 0}, {1, 0}, {1, 2}, {2, 1}, {0, 1}, {0, 2}, {2, 2}}))
	fmt.Println(tictactoe([][]int{{0, 0}, {1, 1}}))
}

func tictactoe(moves [][]int) string {
	row := make([]int, 3)
	col := make([]int, 3)
	diag := 0
	antiDiag := 0

	mIdx := 0
	for ; mIdx < len(moves); mIdx++ {
		if mIdx%2 == 0 {
			row[moves[mIdx][0]]++
			col[moves[mIdx][1]]++
			if moves[mIdx][0] == moves[mIdx][1] {
				diag++
			}

			if moves[mIdx][0]+moves[mIdx][1] == 2 {
				antiDiag++
			}
		} else {
			row[moves[mIdx][0]]--
			col[moves[mIdx][1]]--
			if moves[mIdx][0] == moves[mIdx][1] {
				diag--
			}

			if moves[mIdx][0]+moves[mIdx][1] == 2 {
				antiDiag--
			}
		}

		if row[moves[mIdx][0]] == 3 || col[moves[mIdx][1]] == 3 || diag == 3 || antiDiag == 3 {
			return "A"
		}

		if row[moves[mIdx][0]] == -3 || col[moves[mIdx][1]] == -3 || diag == -3 || antiDiag == -3 {
			return "B"
		}
	}

	if mIdx == 9 {
		return "Draw"
	}

	return "Pending"
}
